Figure 8

Model for regulation of AmpC β-lactamase induction by AmpR, AmpP and AmpG in P. aeruginosa. In Enterobacteriaceae as well as P. aerugniosa, the induction of β-lactamase expression is due to the action of the LysR transcriptional regulator, AmpR. In vitro studies suggest that AmpR can act as either a repressor or an activator, depending upon the presence of different peptidoglycan remodelling intermediates. In this study, it is shown that unlike previously characterized systems, P. aeruginosa has two putative AmpG permease paralogs, AmpG and AmpP. Expression of AmpP is inducible by β-lactam in an ampR-dependent manner. The ampP gene also appears to repress its own expression independent of β-lactam through an unknown mechanism. Although not observed to be induced by β-lactam in a PAO1 background, expression of ampG also appears to be repressed by ampP in the presence of β-lactam (see text for details).